This is a request for a dissertation research grant (PAR-99-139) designed to stimulate minority doctoral candidates to pursue research careers in mental health. The specific aims are to: 1) develop a theoretical model, the Structural Inequality Network Model (SINM), to examine how social networks and social support mediate and/or buffer the influence of neighborhood race-specific inequality and segregation on multiple mental and behavioral problems (i.e., depression, delinquency, suicide, substance abuse, and violence) among adolescents; 2) develop measures of racial inequality, and racial segregation at the neighborhood level that move beyond traditional and static measures of poverty, unemployment, and female-headed households with emphasis on the methodological properties of the inequality indices, their theoretical grounding, and their integration into the development and testing of the SINM; and 3) examine how and whether race-specific inequality and segregation directly and indirectly (through social networks and social support) affect each outcome. To accomplish these aims, this study will use the National Longitudinal Study of Adolescent Health, a sample of 80 high schools and 52 middle schools in the United States. These data provide a nationally representative sample of students (and racial/ethnic over-samples) that links adolescents to a wide range of contextual variables at Census block, Census tract, county, and state levels. To examine the simultaneous impact of individual and neighborhood characteristics, this proposal uses hierarchical linear modeling, which allows researchers to separate the impact of neighborhood-level errors from individual-level errors and thus produces correct standard errors and efficient parameter estimates. This research is expected to significantly contribute to the knowledge base of the impact of social context on adolescent health. There have been few systematic attempts to build a formal theoretical model that accounts for ethnic differences in the impact that community factors, such as inequality and segregation, have on adolescent mental and behavioral health. This study is particularly timely since inequality is increasing across U.S. communities and racial segregation continues.